This invention relates to a substrate transfer system for transferring a substrate such as a silicon (Si) wafer using a robot hand.
As shown in Japanese patent unexamined application publication No. 9-285982, a conventional substrate transfer system for supporting and transferring a plurality of substrates has a structure that at least two end-effectors are located in a surface parallel to a horizontal plane, and positioned in a front and back direction parallel to a transfer direction, and can be rotated about a center position. Employing this kind of structure has made it possible to simultaneously transfer and interchange a plurality of substrates.
FIGS. 6(a) and 6(b) show a substrate transfer system according to a conventional manner. In the substrate transfer system, as described above, an end-effector part 6 which is nearly shaped like H in a surface parallel to a horizontal plane, is structured so as to include a rotational axis in its central position, and connected with a robot hand through the rotational axis such that end-effectors 5 are parallel to a transfer direction. After two substrates are simultaneously set on a forward end-effector 13 in a first step, the end-effector part 6 rotates 180xc2x0 around the rotational axis that is formed in the central part thereof in a second step, and then, two substrates are simultaneously set on a rearward end-effector 14 in a third step. Thus, the conventional substrate transfer system can simultaneously set and transfer four substrates, thereby largely shortening time for transferring substrates. The minimum rotational radius of the substrate transfer system is a radius of a locus circle 11 around the rotational axis formed in the central part of the end-effector, in which a distal end of the end-effector is inscribed.
A substrate transfer system according to an alternate conventional manner, as shown in FIGS. 7(a) and 7(b), is equipped with two end-effectors 5 and a sensor arm 12 which are spaced at equal angles of 120xc2x0 in a surface parallel to a horizontal plane, structured so as to include a rotational axis in its central part, and connected with a robot hand through the rotational axis so as to maintain the end-effectors 5 or sensor arm 12 to be parallel to a transfer direction.
In the above substrate transfer system, the substrate is set on the end-effector that is located parallel to a transfer direction in a first step, and after that, the end-effector part 6 rotates 120xc2x0 around the rotational axis formed in the central part thereof in a second step, then, another substrate is set on another end-effector in a third step. Consequently, the substrate transfer system can simultaneously set and transfer two substrates, and the 120xc2x0 rotation of the end-effector part 6 faces the sensor arm 12 toward a substrate cassette (in which substrates to be transferred are contained), and driving the sensor arm 12 in an up-and-down direction allows a substrate searching operation and so forth. As in the case of the previously-mentioned substrate transfer system, the minimum rotational radius of this substrate transfer system is also the radius of the locus circle 11 around the rotational axis formed in the central part of the end-effector part, in which the distal end of the end-effector is inscribed.
In recent years, in order to enhance productivity, the need for reducing the installation area (space reduction) has been heightened in a substrate processing equipment in which the substrate transfer system is mounted. For this purpose, an area for the substrate transfer system is also limited in the substrate processing equipment. Thus, there has been an important object that the substrate transfer system achieves required functions in a minimum installation area. Besides, in order to achieve the reduction of overall processing time in a total processing equipment, it is an important element in a development to strive for the elimination of processes that does not directly relate to a substrate transfer process, or reduction of the substrate transfer time.
The above substrate transfer system according to the conventional manner can simultaneously transfer plural substrates, and makes it possible to eliminate processes by a change-over operation for providing one same robot hand with end-effectors and sensor arm, which is an effective means for reducing the overall time for processing. However, providing the end-effectors on which plural substrates or a sensor arm are mounted on a same plane, the conventional substrate transfer system increases its minimum rotational radius, thereby making the installation area of the system itself larger.
This invention is made to solve the above-mentioned problems. The first object of the present invention is to provide a substrate transfer system comprising plural end-effectors or plural end-effectors and sensor arm, which achieves a smaller rotational radius than that in the case of the conventional system, thereby contributing toward the reduction of an installation area for a substrate processing equipment.
In order to achieve the above-mentioned objects, according to one aspect of the present invention, a substrate transfer system which transfers a substrate such as a silicon wafer by using a robot hand: wherein said robot hand is equipped with at least two end-effectors each having a surface for mounting the substrate; wherein said end-effectors are placed such that said surface for mounting the substrate is along with a periphery of a cone having a vertical angle at 2xcex8 angle with respect to a central axis at arbitrary xcex8 angle to a horizontal plane as axis, and the end-effectors rotate along with the periphery of the cone pivoting on said central axis; and wherein changing over each of end-effectors from one side to another in a horizontal position, interchanges on one same robot hand at least two substrates to be processed, and besides simultaneously transfers at least two substrates.
According to another aspect of the present invention, a substrate transfer system which transfers a substrate such as a silicon wafer by using a robot hand: wherein said robot hand is equipped with at least one end-effector having a surface for mounting the substrate; and wherein said robot hand is further equipped with a sensor arm having an optical sensor device for detecting that a substrate to be transferred is set on an external container of substrate cassettes; wherein said end-effectors and sensor arm are placed such that said surface for mounting the substrate and the optical sensor device are along with a periphery of a cone having a vertical angle at 2xcex8 angle with respect to a central axis at arbitrary xcex8 angle to a horizontal plane, and the end-effectors and sensor arm rotate along with the periphery of the cone pivoting on said central axis; and wherein changing over each of end-effectors and sensor arm in a horizontal position, interchanges substrates on one same robot hand when the robot hand has plural end-effectors, and besides the optical sensor device carries out a substrate searching operation.